The invention relates to an optoelectronic module and to a method for its production. A preferred application area of the invention is that of low-cost optoelectronic modules that are coupled to Plastic Optical Fiber (POF) optical waveguides.
German Published, Non-Prosecuted Patent Application DE 199 09 242 A1, corresponding to U.S. Pat. No. 6,309,566 to Mueller, discloses an optoelectronic module and a method for its production in which a support with an optoelectronic transducer is positioned in a mold and surrounded with a translucent, moldable material. The moldable material in this case forms a molding that contains a functional surface serving for the coupling. The shaping of the functional surface takes place by a dead mold, which is shaped in a way corresponding to the functional surface and is removed once the moldable material has been introduced into the module housing.
A disadvantage of the prior art production method is that a dead mold is required for shaping the functional surface and this is a disposable part. A further disadvantage is that there is the risk of the functional surface formed by the moldable material in the molding being defectively produced. In particular, there is the risk of an air bubble being formed in the dead mold forming the functional surface during filling with the moldable material so that the functional surface is not formed as a converging lens and, instead, due to the air bubble, is formed as a diverging lens.
The problems described arise to an increased extent if a photodiode or a laser diode that has a smaller diameter in comparison with the component to be coupled on is used as the optoelectronic transducer. So, there is an especially high risk of an air bubble becoming lodged in the correspondingly small depressed formation of the dead mold and leading to the forming of a diverging lens instead of a converging lens.
It is accordingly an object of the invention to provide an optoelectronic module and method for its production that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that avoid the problems explained above and also make it possible to provide a precision-made coupling lens, in particular, even in the case of optoelectronic transducers of small diameter.
With the foregoing and other objects in view, there is provided, in accordance with the invention, an optoelectronic module, including an element, the element being at least one of a transmitting element and a receiving element, a support on which the element is disposed, a module housing defining an opening for introducing the support, the module housing having a coupling region for coupling a component thereat and an interior, a molding of a translucent, moldable material filling the interior of the module housing, and a separate coupling lens for coupling light between the element and the component, the lens disposed adjacent the molding one of in the coupling region and adjacent the coupling region.
Accordingly, in a first aspect of the invention, a coupling lens is disposed in the module housing in or just in front of the coupling region and adjacent to the molding. The coupling lens is formed as a separately produced part that, depending on the method of production used, is inserted into the module housing before or after the filling of the module housing with the molding material.
The coupling lens is, consequently, not formed by the molding but represents a separate part. By using a separately produced part as the coupling lens, it is ensured that the coupling lens has the desired light-shaping properties even in the case of small dimensions.
Preferably, the coupling lens is formed such that it completely closes the coupling region, in particular, toward the interior of the module housing. Such a feature has the advantage that the use of a dead mold or plug formed as a disposable part is superfluous because the module housing is already closed by the coupling lens.
In accordance with another feature of the invention, the coupling lens is accordingly inserted into the module housing before filling of the module housing with the moldable material. Insertion may, in such a case, take place from the inner side or else from the outer side. Preferably, the lens sealingly closes the coupling region with respect to the interior
In accordance with a further feature of the invention, preferably, the coupling lens is shaped such that it has a holding edge, which radially adjoins the light-shaping region of the lens and bears against the module housing in the transitional region to the coupling region. A seal-tight connection with the module housing preferably takes place in such a case by a positive engagement, with peripheral grooves, recesses, or other positively engaging areas being formed in the module housing and/or the holding edge of the coupling lens. The holding edge may be formed integrally with the light-shaping region or represent a separate support, serving for positioning and securing, onto which the light-shaping region, i.e., the actual converging lens, is placed.
In accordance with an added feature of the invention, the module housing has an inner side, the holding edge has an edge region and a peripheral recess in the edge region forming an inner projection and an outer covering region of the holding edge, the lens protrudes with the inner projection into the coupling region and peripherally bears against the coupling region, and the covering region bears against the inner side of the module housing.
In accordance with an additional feature of the invention, the holding edge has a side facing away from the interior of the module housing and forms, on the side, a stop for coupling the component thereon.
In accordance with yet another feature of the invention, the holding edge of the coupling lens is formed with a cranked offset. The periphery of the holding edge in such a case forms, in the direction of the coupling region, a stop for a component to be coupled. The stop is offset axially with respect to the lens vertex in the direction of the coupling region so that there is no risk of an optical waveguide introduced into the coupling region in an abutting coupling with the coupling lens coming directly into contact with the light-shaping region, and possibly damaging the latter thereby.
In accordance with yet a further feature of the invention, the lens is a double lens.
In accordance with yet an added feature of the invention, the molding forms, in the coupling region, a depressed formation that, during the filling of the module housing with the molding, is formed by a projection of a correspondingly shaped dead mold that is removed after filling, and the coupling lens is inserted into this depressed formation of the molding. Unlike in U.S. Pat. No. 6,309,566 to Mueller, the depressed formation does not in such a case form a coupling lens, but represents a receiving and positioning aid for a separately made coupling lens. The coupling lens is, preferably, adhesively bonded into the associated depressed formation of the molding.
In accordance with yet an additional feature of the invention, the element has a smaller diameter than the component.
In accordance with again another feature of the invention, the coupling region is a protruding connecting piece forming a socket for receiving the component.
With the objects of the invention in view, there is also provided an optoelectronic module, including an element, the element being at least one of a transmitting element and a receiving element, a support on which the element is disposed, a module housing defining an opening for introducing the support, the module housing having a coupling region for coupling a component thereat and an interior, and a molding of a translucent, moldable material filling the interior of the module housing, the molding having a functional surface with an outer contour formed during filling of the module housing with the molding by a dead mold having an end face shaped to correspond to the outer contour and removed thereafter, the functional surface having a radially extending structure formed during filling of the module housing with the molding by a radially extending groove of the dead mold.
In accordance with again a further feature of the invention, there is also provided a separate coupling lens for coupling light between the element and the component, the lens being disposed at the functional surface.
With the objects of the invention in view, there is also provided an optoelectronic module, including an element, the element being at least one of a transmitting element and a receiving element, a support on which the element is disposed, a module housing defining an opening for introducing the support, the module housing having a coupling region for coupling a component thereat and an interior, and a molding of a translucent, moldable material filling the interior of the module housing, the molding having a dead-mold-shaped functional surface having an outer contour and a radially extending structure.
In a further aspect of the invention, there is provided an optoelectronic module in which the module housing is filled with a moldable, translucent molding that forms a functional surface, which is formed during the filling of the module housing with the molding by a dead mold that is shaped on its end face in a way corresponding to the outer contour of the functional surface and is removed thereafter. According to the invention, the functional surface has a radially extending structure that is formed during the filling of the module housing with the molding by a radially extending groove of the dead mold. The radially extending groove of the dead mold is perpendicularly aligned during the filling with the moldable material and, consequently, makes it possible for air bubbles forming in the corresponding recess of the dead body to rise up and to be dissipated. As a result, it is ensured that the coupling lens integrated directly into the molding can be produced free from bubbles. However, due to the groove or the structure produced by the latter in the coupling lens, a reduced coupling efficiency must be accepted.
With the objects of the invention in view, there is also provided a method for producing an optoelectronic module with a molding, including the steps of providing a support with an element being at least one of a transmitting element and a receiving element, providing a module housing with an opening for introducing the support therethrough and a coupling region for coupling a component thereon, positioning the support in the module housing to align the element with a predetermined position, at least partly surrounding the support and the element with a translucent, moldable material to form a molding utilizing the module housing as a casting mold, and before filling the moldable material into the module housing, closing the coupling region with a coupling lens aligned with the element.
A first method according to the invention for producing an optoelectronic module is distinguished by the fact that, before filling the moldable material into the module housing, the coupling region is closed with a coupling lens aligned with respect to the transmitting and/or receiving element. The use of a separate dead mold is not required in such a case. The side of the lens facing the interior of the housing is, preferably, of such a nature that the casting compound forms a good bond with the lens during curing. This can be assisted by corresponding selection of the material of the lens.
With the objects of the invention in view, there is also provided a method for producing an optoelectronic module with a molding, including the steps of providing a support with an element being at least one of a transmitting element and a receiving element, providing a module housing with an opening for introducing the support therethrough and a coupling region for coupling a component thereon, positioning the support in the module housing to align the element with a predetermined position, at least partly surrounding the support and the element with a translucent, moldable material to form a molding utilizing the module housing as a casting mold while placing a dead mold in the coupling region, forming a depressed formation in the molding material with a projection of the dead mold during the filling of the module housing with the molding material, removing the dead mold after filling the moldable material in the module housing, and inserting a coupling lens into the depressed formation after the dead mold has been removed.
A second method for producing an optoelectronic module according to the invention uses a separate dead mold and is distinguished by the fact that, during the filling of the module housing with the molding, a depressed formation is formed in the molding material by a projection of the correspondingly shaped dead mold and the coupling lens is inserted into such a depressed formation once the dead mold has been removed. The depressed formation in such a case represents a receiving and positioning aid for the coupling lens inserted after curing of the molding material.
With the objects of the invention in view, there is also provided a method for producing an optoelectronic module with a molding, including the steps of providing a support with an element being at least one of a transmitting element and a receiving element, providing a module housing with an opening for introducing the support therethrough and a coupling region for coupling a component thereon, positioning the support in the module housing to align the element with a predetermined position, placing a rear side of a coupling lens on an end face of a dead mold, the end face of the dead mold being shaped to correspond to the rear side of the coupling lens, and introducing the coupling lens into the module housing with the dead mold, at least partly surrounding the support and the element with a translucent, moldable material to form a molding utilizing the module housing as a casting mold while keeping the dead mold in the coupling region, holding the coupling lens with the dead mold until the module housing is filled with the molding material, and removing the dead mold after filling the moldable material in the module housing.
A third method for producing an optoelectronic module according to the invention likewise uses a separate dead mold and is distinguished by the fact that a coupling lens is disposed on the end face of the dead mold, is introduced into the module housing by the dead mold, and is held by the latter until filling with the molding, the end face of the dead mold being formed in a way corresponding to the rear side of the lens. The side of the lens facing the interior of the housing is in such a case, preferably, of such a nature that the casting compound forms a good bond with the lens during curing.
This variant of the invention has the advantage that the coupling lens is brought into the desired position in the interior of the housing by the dead mold and no stop for the coupling lens is required on the housing. The coupling lens is held in the housing by its adhesive bond with the molding.
With the objects of the invention in view, there is also provided a method for producing an optoelectronic module with a molding, including the steps of providing a support with a transceiver element, providing a module housing with an opening for introducing the support therethrough and a coupling region for coupling a component thereon, positioning the support in the module housing to align the element with a predetermined position of the coupling region, placing a coupling lens on an end face of a dead mold and locating the coupling lens at the coupling region of the module housing, at least partly surrounding the support and the element with a translucent, moldable material to form a molding utilizing the module housing as a casting mold while keeping the dead mold at the coupling region, holding the coupling lens with the dead mold until the module housing is filled with the molding material, and removing the dead mold after filling the moldable material in the module housing.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an optoelectronic module and method for its production, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.